She complied, moving at a leisurely pace.

Richard unrolled his chart again. "What've we got on the building materials? Where did the stone come from?"

She dug out the engineers' report. "All local. Quarries were found in several places, but nowhere closer than six kilometers,"

"They didn't want to spoil the appearance by chewing up the landscape. That's consistent, at least, with what we've seen elsewhere."

"I guess. Anyway, they must have modified the rock. One theory is that they reworked it using nanotech. There's a lot of feldspar and quartz lying around. Apparently waste material. The wall itself is a kind of enhanced calcite."

"Marble."

"Yes. But better. More durable. More reflective."

"They wanted it to be seen from Quraqua."

"Apparently." They were near the top now.

They closed in on a section that had been burned. "Henry thinks," Richard said, "that the damage dates to around 9000 B.C."

"That's when it was built," she said.

"Somebody got right after it, didn't they?"

"Maybe the builders had a falling out. Quarreled over their little amusement park."

Richard held out his hands in supplication. "As good a guess as any."

She went back to her screen. "There's a fair amount of trioxymethylene in the soil. Formaldehyde. But only around here. Near Oz."

"That doesn't mean a damned thing to me. My chemistry's godawful. What are the implications?"

"This thing" — she jabbed a finger at the screen—"offers no theories."

The pseudo-city appeared beyond the wall: a dark cross-hatch of wide boulevards and blunt, broad buildings and long malls. A city of the void, a specter, a thing of rock and shadow. Hutch's instincts demanded lights and movement.

"Incredible." Richard barely breathed the word.

It was immense. She took them higher, and simultaneously switched the cabin heater to manual, moving the setting up a notch. The city, like the wall, lay in ruins.

"Look at the streets," he whispered.

They were designed in exact squares. Kilometer after kilometer. All the way out and around the curve of the horizon. Oz was a place of numbing mathematical exactitude, overwhelming even in its state of general destruction. Avenues and cross streets intersected at precise 90-degree angles. She saw no forks, no gently curving roads, no merge lanes. City blocks had been laid out to the same rigorous geometry.

"Not much imagination here," she said.

Richard's breathing was audible. "If there is anything more at war with the spirit of the Great Monuments than this place, I can't imagine what it would be." No burst of inventiveness appeared anywhere. No hint of spontaneity. They called it Oz. But that was a misnomer. If Oz, the original Oz, was a land of wonder and magic, this place was pure stone. Right to the soul.

Hutch disconnected from the vision, and withdrew into the cockpit. The gauges and keyboards and status lamps were all familiar and warm. The aroma of coffee floated in the still air.

Oz had never been intended to shelter anyone. The structures that from a distance resembled houses and public buildings and towers, were solid rock, without even the suggestion of door or window. No bubble, of either plastene or energy, had ever protected the artifact. Henry's teams had found no machinery, no devices or equipment of any kind.

They drifted down the long avenues. Across the tops of marble block-buildings. Many of the blocks were perfect cubes. Others were oblongs. All were cut from flat polished rock, unmarked by any ripple or projection. They came in a multiplicity of sizes.

Hutch looked out over the network of streets. In its original form, before whatever destruction had come on it, the stones had stood straight. No arc curved through the parallels and perpendiculars. No avenue sliced abruptly right or left. No rooftop sloped. No decorative molding or door knob existed anywhere.

They floated down the streets at ground level. The blocks rose above them, ominous and brooding. They passed through an intersection. For the first time, Hutch understood the meaning of the term alien.

"The dimensions of the blocks are multiples of each other," she said. She brought up the numbers. Every block in the construct was divisible into cubes that measured 4.34 meters on a side. Thus, the various calcite forms that lined the squares and avenues could be perceived as so many units high by so many wide. Streets and open areas were divisible in the same way and by the same dimensions.

The commlink chimed. "Dr. Wald, are you there?"

"I'm here, Frank. Hello, Henry."

Hutch activated the video. Only one man appeared, and it was not Henry Jacobi. Frank Carson was about fifty, a trifle beefy, with an open, congenial countenance. He leveled a steady blue gaze at them, appraised Hutch without reaction, and spoke to Richard. "Henry's not here, sir. Things have got a little hectic, and we couldn't spare him."

Richard nodded. "Anything new on the Monument-Makers? New images?"

"Negative."

Richard seemed almost entranced. "Anybody have any ideas what all this means?"

"No, sir. We were hoping you could tell us."

Richard brought up the scheduling for Project Hope on his monitor. They were to blow the icecaps sometime Friday. "I don't suppose Kosmik has changed anything?"

"The deadline? No." Carson's expression showed disgust. "They're on the circuit every day with a fresh warning and countdown status."

Hutch glanced reflexively at the ship's clocks. Not a lot of time.

"Henry asked me to express his regrets. He would have liked to meet you here, but we just have too much happening." He spoke with military crispness. "What would you like to see?"

"How about the center of this place, for a start? And I'm open to suggestion."

"Okay. I assume your pilot has me on her scope?"

Hutch nodded.

"Why don't you follow me?"

She acknowledged, signed off, and fell in behind. "Tell me about Carson," she said.

"You'll like him. He's retired army. One of those gifted amateurs who are a tradition in archaeology. Like yourself." His tone was light, but she understood he was quite serious. "He's Henry's administrator and executive officer." He looked squarely at her. "And his pilot. If Frank weren't around, Henry would have to behave like a manager. As it is, Frank does all the routine stuff, and Henry gets to be an archeologist."

"Carson doesn't object to that?"

"Frank likes the arrangement. He's a little rough around the edges, and he has a tendency to overreact. But he's easygoing, and he can get things done without ruffling egos. He enjoys the work. The organization could do a lot worse."

Carson's vehicle was starting to descend. "Downtown Oz," said Hutch. The blocks were a little higher here than they were out near the wall. Other than that, the sameness was deadening.

There was a central square, anchored on each corner by a squat tower, or by the ruins of one. The square was about a half-kilometer on a side. A fifth tower, a unit shorter than the others, had been raised in the exact center. Each was as quadrilateral as everything else in Oz.

Richard was half out of his seat, trying to get a better look. "Tilt this thing a little, will you? My way—"

Hutch complied.

Two towers were piles of rubble. A third, on the southwest, was scorched. Burned black from the base up. The fourth was almost untouched. "There," Richard said, pointing to the black one. "Tell him to land there."

She relayed the message, and Carson acknowledged. "What are we looking for?" she asked.

He looked pleased. "How much do you know about the symmetry of this place, Hutch?"

"Not much. Just that it's there. What's to know?"

"Put a few square kilometers on the screen."

"Sure." She brought up a view centered on the middle tower.